benjamin



G. H. BENJAMIN;

ART or MANUFACTURING srm. APPLICATION FILED DEC-5.1914.

1,3 1 4,384 Patented Aug. 26, 1919 G1. 1 fix 0 G. H. BENJAMIN.

ART OF MANUFACTURING STEEL.

APPLICATION FILED DEC-5.1914.

1,314,384, latent ed Aug. 26, 191$).

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(/l i a @2572 J UNITED STATES PATENT GEORGE HILLARD BENJAMIN, OF NEW YORK, N. Y.

ART OF MANUFACTURING STEEL.

To all whom it mqy concern:

Be it known that I, GEORGE HILLARD BENJAMIN, a citizen of the United States, residing at New York city, in the county and State of New York, have invented certain new and useful Improvements in the Art of Manufacturing Steel, of which the following is a specification.

My invention consists in certain new and useful improvements in electric melting furnaces, and the methodemployed for operating such furnaces.

The object of my invention is the con-.

struction of a furnace wherein ---the E. M. F. of the current used to operate the arcs is maintained constant andthe temperature effects of the are varied, as required-in the metallurgical operations taking place -within the furnace.

The temperature of an electric arc is known to be independent of its thickness or of the current passingg'i the temperature can be reduced by lowering the E. M. F. of the current and changing the length of the are. For economical reasons it is best to maintain a given E. M. F. and temperature. The practical utilizable temperature of an electric arc is variously stated to be between 3500 and 4000 centigrade. My invention contemplates maintaining an arcof fixed temperature, and in varying the distance between the arc and the materialunder treatment, in accordance with the temperature which it is desired to exhibit. Thus, given an arc of fixed temperature, I

may, as desired, vary the distance between the arc and the material under treatment. -The accompanyin drawings, which are largely diagrammatic, will serve to illustrate such a construction of furnace as may be used, as well as the method of operating the furnace.

Figure 1 is a vertical section and partial elevation showing the various parts of the furnace and its operating mechanism in the position the parts will occupy when the arc and the material under treatment are nearest together. Fig. 2 is'a horizontal section, taken on the line II- -II of-Fig. 1. Fig. 3 is a horizontal section and partial plan, taken on the line III'I-II of Fig. 4. Fig. 4 is a vertical section and. partial elevation, corresponding to Fi treatment in the posi- Specification of Letters Patent. Patented Aug, 26, 1919.

Application filed December 5, 1914. Serial No.

nected to a source of electric energy 12. 13

indicates mechanism for operating the carbons, whereby an are 14 will be formed between their contiguous ends. 15 indicates a door in the body of the furnace provided with suitable closures 16.17. 18 is a pipe in the top of the furnace; 19 indicates the hearth of the furnate. Thehearth has formed in it a pouring door 20. The hearth 19 is adapted to be rotated and tilted, by substantially the same means as described in my prior Patent No. 1,106,486 dated Aug. 11, 1914, to which reference is made for a further description. The hearth, withits rotatin'g and tilting mechanism, is mounted as a whole upon a plate-like casting 21", supported on the top of a piston 22 mounted in a hydraulic cylinder 23. By reason of the "cylinder 23 and piston 22, the hearth and its 19 and its cooperating mechanism is mount-- ed upon the ground, indicated at 24, and

the body of the furnace is connected to the lower end of the piston 22 located in the cylinder '23. In the modified construction, the body of the furnace is moved relative to the hearth. This modified construction is illustrated inmy prior Patent No. 1,080,807 dated Dec. 9, 1913, to which reference is made for further description. 25 indicates material on the hearth, to -.be treated.- The body of the hearth .10, in both constructions shown, consists of a dome roof 26 and depending side walls 27, and the hearth of a horizontal base or floor 28, and upwardly projecting side walls 29. The sidewalls 29 of the hearth are situated within the side walls 27 of the body, and the downwardly extending length of the side walls'27 of the body and upwardly extend ing length of the side walls 29 of'the hearth,

without exposing any metallic portion of the body to the destructive action of the heat Within the furnace, or permit access of external air to the interior of the furnace. In practice I find that considerable variation in temperature effects may be obtained by a-- small vertical movement of the body and hearth relative to each other.

The operation of my improved furnace will be readily understood. lhe arc is established and maintained by causing the flow of a current of definite potential and value between the electrodes which are kept at practically the same distance apart. suming that it is desired to subject the material to be treated to the maximum temperature, the hearth is moved into the position shown in Fig. 1. As the treatment progresses, and assuming that it is desired the material should be subjected to a decreasing.

temperature, the hearth is moved progressively from the position shown in Fig. 1 to the position shown in Fig. 4, i. 6., which represents the final or pouring position.

During the time the material is under treatment, the hearth may be rotated through the influence of the rotating mechanism shown (as described in my prior Patent No. 1,106,486) and when in the final position may be emptied by employing the mechanism shown (as described in my prior Patent No. 1,080,807). During the time the material is under treatment, gases or other bodies may be introduced through the pipe 18 (as is described in. my prior Patent No. 1,106,486). It will be understood that it is immaterial whether the hearth is moved toward the body of the furnace or the contrary,

provided the relative temperature may be varied by such movement. In carrying certain metallurgical operations into effect, it

is beneficial to rotate the hearth when the material on the hearth is subjected to the highest temperature, and to decrease the rotation of the hearth orto stop it entirely as the hearth is moved into zones of lower temperature, and conversely.

I wish it understood that I do not limit myself in any wise to a co ruction in which the rotation of the heart is effected, or to the system of application of the different temperatures. In the treatment of iron for the production of steel, I prefer to subject the-metal and its accompanying slags and fluxes to the highest temperature at the start, and then gradually move the material out of the zone of highest temperature to zones 'of lower temperature, thus giving the material time, to permit the evolution of the contained gases, or combination with introducedslags and fluxes, it being well understood that combinations are best effected at difierent defined temperatures.

Having, thus described my invention, 1 claim:

1. In an electric furnace, the combination of a body portion, means for generating electric heat of constant thermic value, a hearth portion, means for rotating the hearth portion, means for producing relative movement between the means for producing electric heat and the hearth portion and for holding said specified parts in certain defined relations at different intervals during the operation of the furnace, and without exposing any portion of the furnace, except the lining, to the temperature effects of the electric heat.

2. In an electric furnace, the combination of a body portion, electrodes in said body portion, a rotatable and tiltable hearth portion, means for varying the distance ,between the material under treatment on the hearth portion and the electric arc, during the operation of the furnace, and without exposing any part of the interior of the furnace, excepting the lining, to the action of the electric arc.

3. In an electric furnace, the combination of a fixed body portion, a vertically movable hearth portion, means for producing rotary movement of the hearth portion, a series of electrodes located in the body portion and adapted, when fed with an electric current, to produce an arc of definite thermic value at a definite horizontal level in said body portion.

4:. In an electric furnace, of a fixed body portion, a vertically movable hearth portion, means for moving the hearthportion to and from the body portion,

means for moving the hearth portion in a circular direction along a horizontal plane relative to the body portion, a series of electrodes in the body portion, said electrodes the combination located and adapted, when fedwith an elec- I a defined level, means for moving the hearth portion in a vertical direction in the body portion and out of the body portion, and means for rotating the hearth.

6. An electric furnace comprising in its construction a body portion, a hearth portion, means for producing relative motion of i such parts without permitting the access of atmospheric air to the interior of the furnace, electrodes having a defined horizontal position in the bod portion, means for supplying the electro with current to produce an arc of definite thermic value, and means for tilting the hearth, when removed from the furnace structure after the metaling the hearth portion in a circular direction relative to the body portion, both motions being effected without permitting the access of atmospheric air to the body of the furnace, and means for tilting the hearth to discharge its contents when the hearth portion is separated from the body portion.

8. An electric furnace, comprising in its construction a body portion, a hearth portion, means for producing relative nnuion between said body port-ion and hearth portion in a vertical and rotary horizontal direction without permitting the access of air to the body of the furnace, a series of circtrodes arranged so that the are formed between them will occupy a fixed horizontal level, a three phase generator adapted in deliver current to said are and to establish an arc of constant thermic value, and means:

for discharging the hearth when the body 1:

portion and hearth are separated.

In testlmony whereof I afiix my signature, in the presence of two witnesses. 1

GEORGE HILLARD BENJABIIX.

\Vitnesses:

HELEN E. KonLsoH, FRED. R. humans. 

